Have you consideration to how this framework selection affects the entry barrier to contributing/developing in core? How many of the core developers are experienced working with React or Vue? How steep a learning curve will it be for them?

How many of the Calypso developers also develop core?

Has there been accessibility evaluations of each proposed frameworks? Has the accessibility team weighted in on how easily will you be able to fit or retrofit accessibility into React, React native or Vue?

How will this choice affect theme and plugin developers? Will the hooks that core provide for theme and plugin authors change?